Prerequisites

Sets the login password. 9.1(1): The default password is “cisco.” 9.1(2) and later: There is no default password.

You can enter passwd or password . The password is a case-sensitive password of up to 16 alphanumeric and special characters. You can use any character in the password except a question mark or a space.

The password is saved in the configuration in encrypted form, so you cannot view the original password after you enter it. If for some reason you need to copy the password to another ASA but do not know the original password, you can enter the passwd command with the encrypted password and the encrypted keyword. Normally, you only see this keyword when you enter the show running-config passwd command.

Use the no password command to restore the password to the default setting; in 9.1(2) and later, the no form of the command removes the password.

Changes the enable password. By default, the enable password is blank.

The password argument is a case-sensitive password of up to 16 alphanumeric and special characters. You can use any character in the password except a question mark or a space.

This command changes the password for the highest privilege level. If you configure local command authorization, you can set enable passwords for each privilege level from 0 to 15.

The password is saved in the configuration in encrypted form, so you cannot view the original password after you enter it. Enter the enable password command without a password to set the password to the default, which is blank.

Setting the Hostname

When you set a hostname for the ASA, that name appears in the command line prompt. If you establish sessions to multiple devices, the hostname helps you keep track of where you enter commands.

For multiple context mode, the hostname that you set in the system execution space appears in the command line prompt for all contexts. The hostname that you optionally set within a context does not appear in the command line, but can be used by the banner command $(hostname) token.

To set the hostname, enter the following command:

Command

Purpose

hostname name

asa(config)# hostname farscape

farscape(config)#

Specifies the hostname for the ASA or for a context. The default hostname is “asa.”

This name can be up to 63 characters. The hostname must start and end with a letter or digit, and have only letters, digits, or a hyphen.

Setting the Domain Name

The ASA appends the domain name as a suffix to unqualified names. For example, if you set the domain name to “example.com” and specify a syslog server by the unqualified name of “jupiter,” then the ASA qualifies the name to “jupiter.example.com.”

For multiple context mode, you can set the domain name for each context, as well as within the system execution space.

To set the domain name, enter the following command:

Command

Purpose

domain-name name

ciscoasa(config)# domain-name example.com

Specifies the domain name for the ASA.

The default domain name is default.domain.invalid.

Feature History for the Hostname, Domain Name, and Passwords

Table 13-1 lists each feature change and the platform release in which it was implemented.

Table 13-1 Feature History for the Master Passphrase

Feature Name

Platform Releases

Feature Information

Removal of the default Telnet password

9.0(2), 9.1(2)

To improve security for management access to the ASA, the default login password for Telnet was removed; you must manually set the password before you can log in using Telnet. Note : The login password is only used for Telnet if you do not configure Telnet user authentication (the aaa authentication telnet console command).

Formerly, when you cleared the password, the ASA restored the default of “cisco.” Now when you clear the password, the password is removed.

The login password is also used for Telnet sessions from the switch to the ASASM (see the session command). For initial ASASM access, you must use the service-module session command, until you set a login password.

We modified the following command: passwd .

Setting the Date and Time

Note Do not set the date and time for the ASASM; it receives these settings from the host switch.

Setting the Time Zone and Daylight Saving Time Date Range

To set the time zone and daylight saving time date range, perform the following steps:

Command

Purpose

Step 1

clock timezone zone [ - ] hours [ minutes ]

ciscoasa(config)# clock timezone PST -8

Sets the time zone. By default, the time zone is UTC and the daylight saving time date range is from 2:00 a.m. on the first Sunday in April to 2:00 a.m. on the last Sunday in October.

Where zone specifies the time zone as a string, for example, PST for Pacific Standard Time.

The [ - ] hours value sets the number of hours of offset from UTC. For example, PST is -8 hours.

The minutes value sets the number of minutes of offset from UTC.

Step 2

To change the date range for daylight saving time from the default, enter one of the following commands. The default recurring date range is from 2:00 a.m. on the second Sunday in March to 2:00 a.m. on the first Sunday in November.

The key_id argument is the ID you set in Step 2 using the ntp trusted-key command.

The source interface_name keyword-argument pair identifies the outgoing interface for NTP packets if you do not want to use the default interface in the routing table. Because the system does not include any interfaces in multiple context mode, specify an interface name defined in the admin context.

The prefer keyword sets this NTP server as the preferred server if multiple servers have similar accuracy. NTP uses an algorithm to determine which server is the most accurate and synchronizes to that one. If servers are of similar accuracy, then the prefer keyword specifies which of those servers to use. However, if a server is significantly more accurate than the preferred one, the ASA uses the more accurate one. For example, the ASA uses a server of stratum 2 over a server of stratum 3 that is preferred.

You can identify multiple servers; the ASA uses the most accurate server.

Note In multiple context mode, set the time in the system configuration only.

The day value sets the day of the month, from 1 to 31. You can enter the day and month as april 1 or as 1 april , for example, depending on your standard date format.

The month value sets the month. Depending on your standard date format, you can enter the day and month as april 1 or as 1 april .

The year value sets the year using four digits, for example, 2004 . The year range is from 1993 to 2035.

The default time zone is UTC. If you change the time zone after you enter the clock set command using the clock timezone command, the time automatically adjusts to the new time zone.

This command sets the time in the hardware chip, and does not save the time in the configuration file. This time endures reboots. Unlike the other clock commands, this command is a privileged EXEC command. To reset the clock, you need to set a new time with the clock set command.

Information About the Master Passphrase

The master passphrase allows you to securely store plain text passwords in encrypted format and provides a key that is used to universally encrypt or mask all passwords, without changing any functionality. Features that use the master passphrase include the following:

OSPF

EIGRP

VPN load balancing

VPN (remote access and site-to-site)

Failover

AAA servers

Logging

Shared licenses

Licensing Requirements for the Master Passphrase

Model

License Requirement

All models

Base License.

Guidelines and Limitations

This section includes the guidelines and limitations for this feature.

Context Mode Guidelines

Supported in single and multiple context mode.

Failover Guidelines

If failover is enabled but no failover shared key is set, an error message appears if you change the master passphrase, informing you that you must enter a failover shared key to protect the master passphrase changes from being sent as plain text.

Adding or Changing the Master Passphrase

This procedure will only be accepted in a secure session, for example by console, SSH, or ASDM via HTTPS.

Sets the passphrase used for generating the encryption key. The passphrase must be between 8 and 128 characters long. All characters except a backspace and double quotes are accepted for the passphrase.

If you do not enter the new passphrase in the command, you are prompted for it.

Note Use the interactive prompts to enter passwords to avoid having the passwords logged in the command history buffer.

Use the no key config-key password-encrypt command with caution, because it changes the encrypted passwords into plain text passwords. You can use the no form of this command when downgrading to a software version that does not support password encryption.

Step 2

password encryption aesciscoasa(config)# password encryption aes

Enables password encryption. As soon as password encryption is enabled and the master passphrase is available, all the user passwords will be encrypted. The running configuration will show the passwords in the encrypted format.

If the passphrase is not configured at the time that password encryption is enabled, the command will succeed in anticipation that the passphrase will be available in the future.

If you later disable password encryption using the no password encryption aes command, all existing encrypted passwords are left unchanged, and as long as the master passphrase exists, the encrypted passwords will be decrypted, as required by the application.

Step 3

write memory

ciscoasa(config)# write memory

Saves the runtime value of the master passphrase and the resulting configuration. If you do not enter this command, passwords in startup configuration may still be visible if they were not saved with encryption previously.

In addition, in multiple context mode the master passphrase is changed in the system context configuration. As a result, the passwords in all contexts will be affected. If the write memory command is not entered in the system context mode, but not in all user contexts, then the encrypted passwords in user contexts may be stale. Alternatively, use the write memory all command in the system context to save all configurations.

In the following example, you want to key in interactively, but a key already exists. The Old key, New key, and Confirm key prompts appear on your screen if you enter the key config-key password-encryption command and press Enter to access interactive mode.

Disabling the Master Passphrase

Disabling the master passphrase reverts encrypted passwords into plain text passwords. Removing the passphrase might be useful if you downgrade to a previous software version that does not support encrypted passwords.

This procedure works only in a secure session; that is, by Telnet, SSH, or ASDM via HTTPS.

To disable the master passphrase, perform the following steps:

Detailed Steps

Command

Purpose

Step 1

no key config-key password-encryption [ old_passphrase ]]

ciscoasa(config)# no key config-key password-encryption
Warning! You have chosen to revert the encrypted passwords to plain text. This operation will expose passwords in the configuration and therefore exercise caution while viewing, storing, and copying configuration.
Old key: bumblebee

Removes the master passphrase.

If you do not enter the passphrase in the command, you are prompted for it.

Step 2

write memory

ciscoasa(config)# write memory

Saves the runtime value of the master passphrase and the resulting configuration. The non-volatile memory containing the passphrase will be erased and overwritten with the 0xFF pattern.

In multiple mode, the master passphrase is changed in the system context configuration. As a result, the passwords in all contexts will be affected. If the write memory command is not entered in the system context mode, but not in all user contexts, then the encrypted passwords in user contexts may be stale. Alternatively, use the write memory all command in the system context to save all configurations.

Recovering the Master Passphrase

You cannot recover the master passphrase. If the master passphrase is lost or unknown, you can remove it.

To remove the master passphrase, perform the following steps:

Command

Purpose

Step 1

write erase

ciscoasa(config)# write erase

Removes the master key and the configuration that includes the encrypted passwords.

Step 2

reload

ciscoasa(config)# reload

Reloads the ASA with the startup configuration, without any master key or encrypted passwords.

Feature History for the Master Passphrase

Table 13-2 lists each feature change and the platform release in which it was implemented.

Table 13-2 Feature History for the Master Passphrase

Feature Name

Platform Releases

Feature Information

Master Passphrase

8.3(1)

We introduced this feature. The master passphrase allows you to securely store plain text passwords in encrypted format and provides a key that is used to universally encrypt or mask all passwords, without changing any functionality.

Configuring the DNS Server

Some ASA features require use of a DNS server to access external servers by domain name; for example, the Botnet Traffic Filter feature requires a DNS server to access the dynamic database server and to resolve entries in the static database. Other features, such as the ping or traceroute command, let you enter a name that you want to ping or traceroute, and the ASA can resolve the name by communicating with a DNS server. Many SSL VPN and certificate commands also support names.

Note The ASA has limited support for using the DNS server, depending on the feature. For example, most commands require you to enter an IP address and can only use a name when you manually configure the name command to associate a name with an IP address and enable use of the names using the names command.

Prerequisites

Make sure that you configure the appropriate routing for any interface on which you enable DNS domain lookup so you can reach the DNS server. See the “Information About Routing” section for more information about routing.

To configure the DNS server, perform the following steps:

Detailed Steps

Command

Purpose

Step 1

dns domain-lookup interface_name

hostname(config)# dns domain-lookup inside

Enables the ASA to send DNS requests to a DNS server to perform a name lookup for supported commands.

Specifies one or more DNS servers. You can enter all six IP addresses in the same command, separated by spaces, or you can enter each command separately. The ASA tries each DNS server in order until it receives a response.

Step 16 Load the default configuration by entering the following command:

ciscoasa(config)# noconfig-register

The default configuration register value is 0x1. For more information about the configuration register, see the command reference.

Step 17 Save the new passwords to the startup configuration by entering the following command:

ciscoasa(config)# copy running-config startup-config

Disabling Password Recovery

To disable password recovery to ensure that unauthorized users cannot use the password recovery mechanism to compromise the ASA, enter the following command:

Command

Purpose

no service password-recovery

ciscoasa (config)# no service password-recovery

Disables password recovery.

On the ASA, the no service password-recovery command prevents you from entering ROMMON mode with the configuration intact. When you enter ROMMON mode, the ASA prompts you to erase all Flash file systems.Yyou cannot enter ROMMON mode without first performing this erasure. If you choose not to erase the Flash file system, the ASA reloads. Because password recovery depends on using ROMMON mode and maintaining the existing configuration, this erasure prevents you from recovering a password. However, disabling password recovery prevents unauthorized users from viewing the configuration or inserting different passwords. In this case, to restore the system to an operating state, load a new image and a backup configuration file, if available.

The service password-recovery command appears in the configuration file for information only. When you enter the command at the CLI prompt, the setting is saved in NVRAM. The only way to change the setting is to enter the command at the CLI prompt. Loading a new configuration with a different version of the command does not change the setting. If you disable password recovery when the ASA is configured to ignore the startup configuration at startup (in preparation for password recovery), then the ASA changes the setting to load the startup configuration as usual. If you use failover, and the standby unit is configured to ignore the startup configuration, then the same change is made to the configuration register when the no service password recovery command replicates to the standby unit.

Monitoring DNS Cache

The ASA provides a local cache of DNS information from external DNS queries that are sent for certain clientless SSL VPN and certificate commands. Each DNS translation request is first looked for in the local cache. If the local cache has the information, the resulting IP address is returned. If the local cache can not resolve the request, a DNS query is sent to the various DNS servers that have been configured. If an external DNS server resolves the request, the resulting IP address is stored in the local cache with its corresponding hostname.

To monitor the DNS cache, enter the following command:

Command

Purpose

show dns-hosts

Show the DNS cache, which includes dynamically learned entries from a DNS server as well as manually entered name and IP addresses using the name command.